Conventionally, a plurality of screws are employed to fasten a hard disk in a frame inside a computer case. The hard disk is electrically coupled to a circuit board by means of data and power cables. The operating power of the hard disk is supplied by the circuit board. Also, data can be transferred between the hard disk and the circuit board. However, the disassembly of the hard disk is very tedious when a replacement of the hard disk is required due to malfunctioning or upgrading for a new hard disk of higher capacity. First, a user has to detach the cover of the computer case. Next, detach the hard disk from the frame. Next, install a new hard disk in the frame. Finally, fasten the cover on the computer case. It is understood that downsizing is the trend of modern computers. Thus, the prior art arrangement has difficulty in installing a hard disk in the computer or detaching the hard disk from the computer due to narrow internal space of the computer. Hence, a need for improvement exists.